Spark discharge device



Oct, 24, 1944. 3, L R 2,361,218

SPARK DISCHARGE DEVICE Filed Feb. a. 1943 Invent I William LLinlor; 7"? v mwuL/W/a/V m4, /7 by Y Patented Oct. 24, 1944 UNITED STATES PATENT OFFICE SPARK DISCHARGE DEVICE William I. Linlor, Scotia, N. Y., assignor to General Electric Company, a corporation of New York ' Application February a, 1943, Serial No. 475,089

12 Claims.

, age substantially lower than that normally required to break down a spark gap of the given spacing.

Further objects and advantages of my invention will become apparent and my invention will be better understood from the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and forming part of this specification.

In the drawing, Fig. 1 is a side elevational view, partly broken away, of a spark plug provided with an embodiment of my invention; Fig. 2 is a sectional view taken along line 2 -2 of Fig. 1; and Fig. 3 is a partial-sectional view of the lower end of a spark plug provided with another embodiment of my invention.

Referring to the drawing, I have shown my invention applied to a spark discharge device in the form of a spark plug provided with a conventional spark plug barrel ill in which a central electrode l i is supported by a ceramic insulator i2 held in position by a nut ill of the conventional type. The lower or spark discharge end ll of the central electrode l i is formed as an enlarged section and is spaced a desired distance from two sets of discharge electrodes i5 and It to provide a predetermined breakdown gap spacing therebetween for breakdown at a suitable voltage. These electrodes are constructed and arranged to provide an effective tapered spacing between the central discharge electrode I4 and the outer electrodes it by providing auxiliary elements l'l electrically connected by being integrally formed with the inner portions of the elec trodes l6 so as to extend to closely adjacent the central electrode discharge end portion I4. This provides a tapered gap spacing between the electrode l4 and the tapered portion l8 of the elements I1, and an insulating element formed as a sheet insert 19 of insulating material, as shown in Figs. 1 and 2, or as a solidified coating 20 of high dielectric strength, as shown in Fig. 3, which is arranged over the tapered surface I8 of the elements ll to prevent breakdown of the gap between the electrodes, except through that part of the gap between the electrodes, except through that part of the gap having the desired breakdown spacing. The coating 20 may be applied in any suitable manner, as by spraying,

painting, dipping, or other suitable method of 1 applying a thin coating. Such an arrangement provides for electrically stressing the gas between the electrode l4 and the auxiliary insulating element l9, providing progressive ionization of the gas therebetween, ranging from the eflective smaller spark gap spacing at the narrowest part of the tapered portion of the gap to the breakdown spaced gap portion between the electrode l4 and the electrode H6. The operation of this auxiliary element is in effect to provide for the initial ionization of the gas near the apex of the tapered .gap portion, which ionization progressively moves the eflective surface of the electrode it from the metal portion thereof outwardly towards the adjacent surface of the electrode iii to the end of the insulating element It] under which condition the gap breaks down and an electrical discharge takes place between the electrodes l4 and it at a voltage which is substantially less than that which would be required for the breakdown of the gap if no auxiliary elements were present. With this arrangement, discharge of the sparkplug is greatly facilitated under adverse firing conditions, as when the engine and fuel may be very cold or when the voltage supplied to the plug may be lower than is'normally available.

While I have illustrated and described a particular embodiment of my invention applied to a spark plug, modifications thereof and other applications will occur to those skilled in the art. I desire it to be understood, therefore, that my invention is not to be limited to the particular arrangement disclosed, and I intend in the appended claims to cover all modifications which do not depart from the spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means for providing an effective spacing between said electrodes which varies from a relatively small spacing to that of a predetermined breakdown spark gap spacing, and means for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

2. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means for providing an effective tapered spacing between said electrodes which tapers from a relatively small effective spacing to that of a predetermined breakdown spark gap spacing, and means for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

3. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween spaced for an efiective suitable breakdown voltage, means providing for electrically stressing the gas betweensaid electrodes producing progressive ionization of the gas therebetween for electrical discharge therebetween at a voltage substantially less than said suitable breakdown voltage, and means for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired efiective breakdown spacing.

4. A spark discharge device-- having spaced apart electrodes providing a spark discharge gap therebetween spaced for a suitable breakdown voltage, means providing for electrically stressing the gas between said electrodes producing progressive ionization of the gas therebetween for electrical discharge therebetween at a voltage substantially less than said suitable breakdown voltage, and means including an insulating element in said gap between said electrodes, said insulating element preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

5. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means electrically connected to one of said electrodes for providing an eifective tapered spacing between said electrodes which tapers from a relatively small effective spacing to that of a predetermined .breakdown spark gap spacing, and means for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

6. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means for providing an effective tapered spacing between said electrodes which tapers from a relatively small efiective spacing to that of a predetermined breakdown spark gap spacing, and means including an insulating element between said electrodes in said effective smaller than breakdown gap spacing for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

7. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means electrically connected to one of said electrodes providing an effective tapered spacing between said electrodes which tapers from a relatively small effective spacing to that of a predetermined breakdown spark gap spacing, and means including an insulating element trodes except through that part of the gap having the desired breakdown spacing.

between said electrodes in said efiective smaller I than breakdown gap spacing for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

9. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means including the construction and arrangement of said electrodes providing a spacing between said electrodes which varies from a relatively small spacing to that of a predetermined breakdown spark gap spacing for electrically stressing the gas between said electrodes producing progressive ionization of the gas therebetween from said smaller spark gap spacing to said breakdown spaced gap portion, and means between said electrodes in said eifective smaller than breakdown gap spacing for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

10. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means including an auxiliary element electrically connected to one of said electrodes providing an effective spacing between said electrodes which varies from a relatively small eiiective spacing to that of a predetermined breakdown sparkgap spacing for electrically stressing the gas between said electrodes producing progressive ionization of the gas therebetween from said eifective smaller spark gap spacing to said breakdown spaced gap portion, and means including an insulating element between said electrodes in said smaller than breakdown gap spacing for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

11. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means including an auxiliary element electrically connected to one of said electrodes providing an effective tapered spacing between said electrodes which tapers from a relatively small effective spacing to that of a predetermined breakdown spark gap spacing for electrically stressing the gas between said electrodes producing progressive ionization of the gas therebetween in said tapered gap from said efiective smaller spark gap spacing to said breakdown spaced gap portion, and means including an insulating element between said electrodes in said effective smaller than breakdown gap spacing for preventing breakdown of said gap between said electrodes except through that part 101: the gap having the desired breakdown spac- 12. A spark discharge device having spaced apart electrodes providing a spark discharge gap therebetween, means including an auxiliary element forming a tapered end portion on one of 8. A spark discharge device having spaced 3 apart electrodes providing a spark discharge gap therebetween, means for providing an effective spacing bet veen said electrodes which varies from a relatively small spacing to that of a predetermined breakdown spark gap spacing producing progressive electrical .stress of the gas between said electrodes and progressive ionization of the gas therebetween from said smaller spark gap spacing to said breakdown spaced gap portion, and means including an insulating element between said electrodes in said efiective smaller than breakdown gap spacing for preventing breakdown of said gap between said elecsaid electrodes providing an effective tapered spacing between said electrodes which tapers from a relatively small effective spacing to that of a predetermined breakdown spark gap spacing for progressively electrically stressing'the gas between said electrodes producing progressive ionization of the gas therebetween in said tapered gap from said effective smaller spark gap spacing to said breakdown spaced gap portion, and means including an insulating element between said electrodes in said eifective smaller than breakdown gap spacing for preventing breakdown of said gap between said electrodes except through that part of the gap having the desired breakdown spacing.

WILLIAM I. LINLOR.

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